A method for enabling xerographic printing on envelopes, and more specifically for providing apparatus for envelopes to pass through the xerographic engine long edge first, flap trailing and with the glue side of the flap away from the photoreceptor.
It is well known that addresses can be printed on business size envelopes in xerographic printers, see U.S. Pat. Nos. 4,397,542, 5,069,434 and 5,099,633. The envelope is transported through the printer longitudinally, short edge first, so that the paper path nips, normally designed to handle 81/2 by 11 inch paper sheets, in the case of #10 business envelopes will always be in contact with the 4 by 91/2 inch envelope.
One problem associated with this process is that the flap adhesive may melt during the xerographic processing or be activated by moisture driven out of the paper, either sealing the envelope or contaminating the machine. This has been solved to some degree, see U.S. Pat. No. 4,898,323, by providing a high temperature adhesive. However, in the case where the envelope has a flap, the better solution to the contamination problem is to keep the flap closed.
Another problem associated with this arrangement is that the envelope is not perfectly symmetrical in construction from the top surface to the bottom and corner to corner. Furthermore, the envelope is processed through fuser roll nips that are balanced for minimizing the wrinkling of paper, and therefore are not balanced for minimizing the wrinkling of envelopes, and a certain amount of wrinkling of the envelope usually results as it passes through the roller nip of the roller fuser rolls. Also, an envelope may contain as many as four layers of paper from one side to the other which may result in an area on the envelope where the toner does not transfer properly.
There is thus a need in the industry for a printer process that will produce quality printing on envelopes at a high throughput rate.